Casing perforator



F 1 c. B. MARGRAVE v 2,108,172

CAS ING PERFORATOR Filed Jan. 11, 1957 2 Sheets-Sheet l Z22 f ezz i or.'18 Char/es B. Morgm ve HZ iorneys.

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Feb. 15 1938. c. B. MARGRAVE 2,108,172

CASING PERFORATOR Filed Jan. 11, 1937 2 Sheets-Shem. '2

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[221/622 tor C bar/e5 B. Margra l/ Fatented Feb. 15, 193% arcane CASING'rnnr'ona'roa Charles B. ltiiargrave, Los Angeles, (Calif; assignor oione-half to Albert ll. liiireslow, Los Angeles,

Calif.

Application January 111, 1193?, Serial No. 120,026

llli Claims.

My invention pertains to a perforator for perforating well casing suchas the casing of oil wells and provides a type of perforator which givesa clean cut at the perforation and forces the slit metal of the casingoutwardly at the perforation developing a slight fin at the top of theperforation which restricts the entrance of sand with oil into thecasing. Another feature of my invention is that the perforator which hasperforating cutters causes these cutters to have a sliding movementtransverse to the axis of the casing and in which the perforatingcutters or cutter tools thus have a sliding 'motion radially of thecasing and as two tools are employed, these are diametrically opposite.Another'feature of my invention is developing a force to force the toolsthrough the casing by a toggle action, this being produced by a slightlowering of a drill string or the like to force the perforator toolsoutwardly, 20 these being supported by a portion of a string of drillpipe or similar tools resting on the bottom of the well and extendingupwardly to the desired position in which it is desired to perforate thecasing.

Considered in more detail, a further object and feature of my inventionis in the construction of toggle actuated cutter tools operating indiametrically opposite slots, each of which is connected to togglelinks, these being pivoted to a common head and such head being slidablyarranged in a guide block. When this guide block is connected to theupper portion of the string of drill pipe, the assembly may be loweredinto the well and when the bottom of the string below the blocks 35supporting the cutting tools contacts the bottom of the well, thefurther slight lowering of the drill string due to the weight causes themovable head having the toggle links to develop a further downwardmovement, the links thus pressing the cutter tools outwardlydiametrically opposite and thus perforating the casing. A further detailfeature of my invention is in the shape of the cutter tools whichpreferably have a fiat or straight bottom edge, an upwardly and inwardlysloping perforating surface with slightly beveled side edges. Thiscauses the cutter tool to make a clean cut at the bottom of theperforation, this being a sheer cut on the casing. A sheer'cut is alsogiven at the sides of the perforation so that an upper protruding lip isbent outwardly at the top of the perforation. This lip tends to preventsand settling through the opening of the perforation into the casing.Another characteristic of the type of perforator used coupled with thesliding motion is that the perforator may be used to (m. Mil-4B4) crackcement which may be on the outside of the casing. This is an advantageas it sometimes happens that in cementing oil a water bearing stratathat the cement will also cut off a portion of the oil bearing sands.With my type of perforators the casing may not only be perforated butalso the cement on the outside cracked to permit inflow of oil.

My invention is illustrated in connection with the accompanyingdrawings, in which:

Fig. l is a vertical section through my invention taken on the line l--lof Fig. 3 in the direction of the arrows showing the perforator cuttersand toggle links in elevation and also the plug and rod to which theseare connected shown in elevation. In Fig. 1 the cutters are retracted.

Fig. 2 is a section similar to Fig. 1 with the cutters forced outwardlyby the downward movement of the toggle links.

Fig. 3 is a horizontal section on the line 3-3 of Fig. 2 taken in thedirection of the arrows.

Fig. 4 is a detail vertical section on the line 44 of Fig. 2 in thedirection of the arrows showing one of the cutters and the cutter guideopening.

Fig. 5 is a horizontal section on the line 5-5 of Fig. 2 on a reducedscale.

Fig. 6 is a detail plan of one of the perforating cutters removed fromthe assembly.

In my invention a toggle guide block assembly designated by the numeralll consists of a lower block I2 whichhas a flat upper surface I3transverse to the axis of the tool, the side wall M is cylindricalmerging by a rounded corner Hi to a fiat bottom surface l6 from which anintegral solid rod il extends downwardly. The upper block member isheavy and rests on the fiat surface 13 of the lower block. This howeverhas two diametrically opposite guide slots 22 defined by the twoopposite vertical edges 23, the top edge 2i and the surface iii of thelower block forming the bottom wall of the guide opening.

This block is also cylindrical as to its side wall 25 and has roundedcorners 25 merging with the fiat top surface 271. Centrally positionedin the upper block there is a large circular bore 28 and below thisthere are diverging recesses 29 having a sloping upper surface, 30merging with the upper surface M of the guide openings 22, this slopebeing to accommodate the toggle lengths hereinunder detailed. Theserecesses are considerably wider in a transverse measurement indicated at(ii in Fig. 3 to accommodate the toggle links as hereinunder detailed.The two blocks are held together by utilizing a strong and heavy ring 32which rests on the fiat top 21 of the upper block. This ring has aperipheral wall 33 preferably slightly smaller than the diameter of theupper block 28 as to its cylindrical wall 25 and has a central opening34 which is smaller in diameter than the bore 28.

A heavy cylindrical plug 40 having an integral rod 4| preferablycylindrical is part of the toggle actuating assembly, the plug beinglocated in the large bore 28, this plug having an upper shoulder 42engaging underneath the heavy ring 32. This ring and the upper and lowerblocks are securely bolted together by a series of, longitudinal bolts43. Thus by suspending the rod 4| the plug40 may engage underneath thering 32 and suspend the whole block assembly H and a portion of a drillstring as hereinunder described, secured to the lower end of the solidrod l1.

The plug 40 has a recess 44 from its undersurface 45 and in this isfitted the upper end of the toggle plate 46. This plate is rectangularin horizontal section as indicated in Fig. 3 and has a shoulder 41bearing on the undersurface 45, this plate being secured by a pin 48 orthe like extending through the plug 40 and through an opening in theportion of the plate inserted in the recess 44.

The toggle assembly 50 has two pair of parallel toggle links 5|.The-upper end 52 of each pair is pivoted to the toggle plate 46 bysubstantial toggle pins 53. The lower ends 54 are pivoted also bysubstantial pivot pins 55 to the perforating cutting tools 56. Suchperforating tools have a flat lower surface 51, parallel sides 58 and aflat top 59. There is a sloping cutting end 60 with a sharp forwardcutting point 6|. The two side edges of the sloping face of the cutterare slightly beveled as indicated at 62 and also adjacent the sharp edge6| there may also be a slight bevel 63.

The manner of assembling the tool in a string of drill pipe may be inany suitable way, the manner illustrated showing an upper sub 10, theupper end of the solid rod 4| being threaded therein as indicated at 1|,these being tight threads not intended to unscrew in disconnectingstands of the drill string. This sub is shown as having a taper threadedbox 12 to which a pin of a tool joint coupling may be connected, thisforming part of the drill string with the tool inserted in the string.As it is usually necessary to perforate the casing at some distanceabove the bottom of the well, the lower solid rod H is shown as threadedinto a lower sub 15, this having a tight fitting threaded section l6.This sub may also have a pin on its lower end for connecting to thelower part of the drill string by a tool joint coupling and below thisthere may be a further portion of the drill string indicated at 11. Thisis shown as resting on the bottom of the well hole indicated at 18. Thebore of the hole is indicated at 19 and the casing at 80. It sometimesoccurs that outside of the casing there is a body of cement indicated at8|, and although the cement is usually 'for the purpose of cutting offwater from the well,

sometimes this cement is found to be in an oil bearing strata.

In the operation of my invention it will be understood that a survey ofthe well has made it known what locality of the casing is to beperforated, therefore the drill string is made up with the perforatingtool in the proper place so that the lower end of the string may rest onthe bottom of the hole. In lowering, the plug 40 engages the ring 32 andcarries the weight of all of the string below the solid rod 4|. Whilethe string is being lowered the toggle links are in the upper positionand the tools are retracted as shown in Fig. 1.

- When the lower end of the drill string as indicated at H contacts thebottom of the hole and the upper part of the string is lowered, theweight proximately a straight out, this causing a lip indicated at 82 tobe forced outwardly above the perforation. Such lip tends to restrictthe flow of sand into the casing. The perforating cutters are alsooperative to crack any cementing wall on the outside of the casing andthus allow a flow of oil through such cement.

Various changes may be made in the details of the construction withoutdeparting from the spirit or scope of the invention as defined by theappended claims.

I claim:

1. A casing perforator comprising in combination a substantial blockassembly having diametrically opposite straight transverse guideopenings and a central bore connected thereto, perforators rectilineallyslidably mounted in the openings, a plug slidably mounted in the bore,toggle links, means connecting the toggle links between the plug and theperforators, a supporting means connected to .the lower end of the blockassembly for supporting the block in a desired position in a wellcasing, means attached to the plug for connection to a string of drillpipe for raising and lowering the plug whereby when the plug is elevatedthe perforators are retracted and when the plug is lowered. saidperforators are forced outwardly to perforate the casing.

2. A casing perforator comprising in combination a block assembly havinga lower block and an upper block, said blocks having contiguoushorizontal surfaces with a pair of diametrically ing the upper ends ofthe toggle links to the said plug, a supporting means connected to thelower block for retaining the block assembly in the desired position ina well casing, means connected to the plug for attachment to a string ofdrill pipe whereby the block assembly may be lowered in a casing andwhen the supporting means supports the block assembly in the desiredposition the continued downward movement of the plug forces theperforators outwardly laterally to perforate the casing.

3. A casing perforator as claimed in claim. 2, the supporting meanscomprising a rod connected to the lower block, a sub connected thereto,said sub being adapted to engage the bottom of the well hole.

4. A casing perforator comprising in combination a block assembly havinga lower block with a horizontal upper surface, an upper block with acomplementary surface and a pair of diametrically opposite straightradial guide openings exopenings and bearing on the upper surface of thelower block, toggle links connected to the perforators, means pivotallyconnecting the upper ends of the toggle links to the said plug, theplugv having a shoulder engaging the under side of the said ring, meansfor attaching the plug to a string of drill pipe, a supporting meansconnected to the lower block for supporting the block assembly in adesired position in a well casing, the said block assembly and thesupporting means being adapted to be lowered into a well suspended fromthe plug and with the perforators retracted, a downward movement of theplug when the-block assembly is held stationary being adapted to forcethe perforators diametrically outwardly to perforate the casing. a

5. A casing perforator as claimed in claim 4, theperforators having aflat lower surface terminat'ng in a horizontal outer cutting edge, anupwardly sloping. cutting end from the cutting edges whereby inperforating the casing an outwardly projected lip is. formedabove theperforation.

6. A casing perforator as claimed in claim 4, the means connecting thetoggle links to the plug comprising a toggle plate connected to thelower end of the plug, the upper ends of the toggle links beingpivotally connected to the said plate.

7. A casing perforator comprising in combination a block assembly havinga lower block with a horizontal upper surface, a rod projectingdownwardly and having means for connection to a lower sub, an upperblockhaving a flatJower surface contacting the upper surface of the lower Iblock, the upper block having'diametrically opposite straight radialguide openings forming two uide slots defined by opposite verticalsides, a horizontal top and the upper surface of the lower block, theupper block having a central bore connecting with the said slots, aringon the top of the upper block and having an opening smaller" than thesaid bore, bolts connecting the two blocks and the ring, a plug slidablymounted in the .said

bore and having-a toggle plate connected thereto at the bottom, a pairof toggle links pivotally connected to said plate, a pair of perforatorsin the said slots and pivotally connected to the lower end of the togglelinks, means connecting the plug and adapted for attachment to the lowerend of a; string of drill pipe whereby the assembly of the blocks andthelower sub may be lowered into awell, the ring engaging the said plugand thereby retracting the perforators, the said sub on engaging thebottom of the well hole forming a solid support for the block assemblywhereby the continued downward movement of the plug forces theperforators rectilineally outwardly to perforate the casing.

8. A casing perforator as claimed in claim 7, I

the perforators being rectangular in vertical cross-section and having aflat lower surface with a horizontal. outside cutting edge and upwardlysloping cutting ends, the said ends on each side having a slight bevelwhereby on perforating a casing a clean horizontal sheer cut is formedat the bottom of the perforation and lips are out-- wardly bent at theupper part of the perforation.

9. A casing perforator comprising in combination a block assembly havinga lower block with a horizontal upper surface, an upper block having acomplementary lower horizontal surface with a pair of diametricalstraight radial .slots in its lower surface defining with the uppersurface of the lower block straight radial guide openings rectangular incross section, the upper block having enlargements at the inner end ofsaid slots and a central circular bore connecting to said enlargements,a ring on the upper end of the upper block, bolts through the ring andthe two blocks, a cylindrical plug mounted in the bore and having anupper shoulder engaging the ring, perforators rectangular in crosssection slidably rectilineally transversly in the said slots, togglelinks having their lower ends pivotally connected to the inner ends ofthe perforators, means pivotally connecting the upper ends of the togglelinks to the said plug, the lowerblock having a solid lower rod of muchsmaller diameter than .the block extending downwardly and a lower subconnected to said lower rod, the plug having a solid upper rod extendingupwardly through the ring and having means for connection to astring ofdrill pipe whereby the assembly may be lowered into a well, the shoulderof the plug engaging the said ring and when the lower sub contacts thebottom of the well hole the continued downward movementof the plugforces the perforators outwardly.

' 10. A casing perforator as claimed inclaim 9,

o. n'umomvn.

